camera orthographic/perspective
The behavior of the viewport, reverting to a perspective view from any of the set orthogonal views, is a User Preference, and can be set here:





The 2.7x system of layers and render layers has been entirely replaced with Collections and View Layers. which are much more flexible, and in the end, easier to use. Beyond the manual,  there are tutorials out there.. I hope this helps by giving you productive search terms.